<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #btn {
            width: 200px;
            height: 30px;
        }
    </style>
</head>

<body>
    <button id="btn">
        点击获取验证码
    </button>
    <script src="button.js"></script>
</body>

</html>